Field of the Invention
The present invention relates to an attitude control apparatus and method, and more particularly to an antenna attitude apparatus and control method for receiving satellite broadcasts in a vehicle such as a car.
Since satellite communications first became a reality there have been moves toward receiving radio waves from satellites not only in fixed structures such as buildings but also in cars and other vehicles. A high-gain antenna, i.e., an antenna with high directionality, is required to receive the weak radio waves from a satellite. As such, when the aim is to receive satellite radio waves in a vehicle, controlling the attitude of the antenna becomes a problem that has been the subject of numerous methods and techniques that have been proposed.
One example is the antenna device for satellite communications disclosed in Japanese Patent Publication SHO 61(1986)-28244. Stated briefly, the device of the disclosure employs a communications antenna and a rate gyroscope on a flywheel type stabilizing stand to maintain the attitude of an antenna that has been initially set to the direction for receiving the transmissions.
However, high-gain antennas for receiving weak signals from satellites are relatively large and heavy, and to install them so they maintain their stability necessitates the use of a flywheel having a large inertia, i.e., a heavy flywheel, which makes them unsuitable for installing in small vehicles.
Owing to the maneuverability of small vehicles, attitude changes tend to be intensive, and to maintain the initial attitude over long periods in the face of such intensive changes of attitude requires the use of a large rate gyroscope having a large inertia, which is another reason that makes such an apparatus unsuitable for small vehicles.